The pre-iOS 7 back button consolidated these things into a single button shape that tapers into an arrowhead on the left side, and it housed a text description of where the button would lead you. It basically did three jobs with a single element. First, it visually signaled the way back, so that even if you didn’t read the descriptor text, you would still recognize the button’s function instantly. Second, if you did read what it said, it gave you the title of the previous view, without forcing you to tap and hold or take some secondary action to reveal that information. And finally, unlike the new back button in iOS 7, it was explicit about what you could tap and where; the target area was clearly demarcated by the button shape, and managed to do so without crowding the title of the view to its right (by contrast iOS 7’s new back button text often seems to run right into the title of the screen)

Just as importantly, the old back button was a visually pleasing design. Its left side wasn’t just a standard, angular arrowhead — its angles were ever so slightly sloped, softening the shape just enough to suggest that going back would be smooth and instantaneous.

The effect was tremendously elegant, in a very subtle way, and it became a hallmark of iOS apps. No other operating system’s back buttons worked quite the same way, but even better most iOS developers who customized the look of this button would preserve its basic shape, size and function. They might have changed up the color, swapped in a new typeface, or even altered the dimensionality of the button so that it was flat or embossed, but they rarely strayed very far from the original. I always liked to look closely at third party developers’ renderings of this button, to see if they replicated those gentle curves on the arrowhead. In my mind, the very best designed iOS apps always captured that tiny but important detail.